freightliner 108SD, Driver Manual

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5.
Ensure the O-ring is present inside the fuel fill
port. If the O-ring has been dislodged or is miss-
ing, the station dispensing nozzle will not con-
nect securely to the fill port.
6.
Turn the selector knob on the service pump to
the VENT position, if equipped.
7. Connect the quick coupling on the dispensing
nozzle securely to the vehicle fuel fill port.
8. Turn the selector knob on the service pump to
the FILL position, if equipped.
IMPORTANT: If at any time the service pump or
vehicle begins to vent CNG uncontrollably, notify
a station attendant or activate the service sta-
tion emergency shut-off switch to cease the flow
of CNG.
9. Switch on the service pump. A slight hissing
noise may be heard as the fuel cylinders fill.
10. Watch the pressure gauge on the service pump.
When the gauge reads approximately 3600 psi
(24 800 kPa), or when the fill pressure stops
climbing, the CNG cylinders are full. The service
pump will shut itself down automatically. See
Table 19.1 for pressure compensation values
based on ambient temperatures.
11. Move the selector knob on the service pump to
the VENT position, if equipped. A short hiss will
be heard as a small amount of natural gas is
vented into the hose.
WARNING
Do not attempt to remove the fill station nozzle
from the tank fill fitting until venting of pressure
is noted. If no venting occurs, ask for assistance
from the station attendant. Removing an un-
vented coupling could result in an uncontrolled
hose, which could lead to property damage or
personal injury.
12. Remove the station dispensing nozzle from the
vehicle fill port.
13. Install the dust cap on the vehicle fuel fill port
and close the fuel panel access door.
LNG Vehicle Fueling
The LNG fuel tank is designed to be filled from any
LNG fuel source that has a 100 micron or finer fuel
filter and a fuel delivery pressure between 120 and
225 psi (827 and 1551 kPa).
The LNG fuel tank is designed to be top-filled
through a single hose with no vent return. As cold
LNG is sprayed into the vapor space of the tank, the
cold liquid condenses the vapor and creates space
for itself inside the tank, eliminating any need to vent
during the filling process.
The LNG tank is equipped with a small internal ul-
lage tank for vapor space, which allows for fuel ex-
pansion and increases vehicle standby time. When
an LNG tank is full, fuel can continue to flow into the
ullage tank. However, if the ullage tank is completely
filled during fueling, standby time will be reduced to
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1. Fuel Cylinder Storage Box
2. Fuel Cylinder Shutoff Valves (qty 5)
3. High-Pressure Gauge
4. Low-Pressure Gauge
5. Fuel Fill Port
6. Dust Cap
7. Manual Shutoff Valve
8. Fuel Panel Access Door
Fig. 19.1, CNG Fuel Cylinder Storage Box (5-cylinder
system shown)
Natural Gas Vehicle
19.3